North American physicians emerge from their medical training with a wide array of professional beliefs and values. Many are thoughtful and introspective. Many are devoted to patients' welfare. Some bring to their work a broad view of social responsibility. Nonetheless, the authors contend that North American medical education favors an explicit commitment to traditional values of doctoring-empathy, compassion, and altruism among them-and a tacit commitment to behaviors grounded in an ethic of detachment, self-interest, and objectivity. They further note that medical students and young physicians respond to this conflict in various ways. Some re-conceptualize themselves primarily as technicians and narrow their professional identities to an ethic of competence, thus adopting the tacit values and discarding the explicit professionalism. Others develop non-reflective professionalism, an implicit avowal that they best care for their patients by treating them as objects of technical services (medical care). Another group appears to be "immunized" against the tacit values, and thus they internalize and develop professional virtue. Certain personal characteristics of the student, such as gender, belief system, and non-medical commitments, probably play roles in "immunization," as do medical school features such as family medicine, communication skills courses, medical ethics, humanities, and social issues in medicine. To be effective, though, these features must be prominent and tightly integrated into the medical school curriculum. The locus of change in the culture of medicine has now shifted to ambulatory settings and the marketplace. It remains to be seen whether this move will lessen the disjunction between the explicit curriculum and the manifestly contradictory values of detachment and entitlement, and the belief that the patient's interest always coincides with the physician's interest.